A conventional image forming apparatus, for example, a copier, a laser beam printer, or a facsimile machine, includes a fixing apparatus that fixes an unfixed toner image transferred onto the recording material. The recording material bearing the unfixed toner image is transported to a nip portion formed by a heating roller and a pressure roller of the fixing apparatus, and then the unfixed toner image is fixed onto the recording material. In this configuration, a toner image in a melted state comes into contact with a surface of a fixing roller during fixation, which may cause the recording material to wrap around the fixing roller. A conventionally proposed configuration for preventing wrapping of the recording material around the fixing roller includes a separating claw provided downstream of the nip portion of the fixing rollers in a transporting direction. If a leading end of the recording material is mostly wrapped around the fixing roller, the separating claw forcibly peels off the leading end of the recording material from the fixing roller. Another configuration is proposed with a cleaning member that removes toner deposited on the fixing roller.
In order to prevent wearing of the separating claw from reducing separation capability and prevent the applied amount of oil from decreasing in accordance with the high transport speed of the recording material, recently, the wrapping of the recording material around the fixing roller needs to be further prevented. Conventionally, two sensors for detecting the recording material are provided upstream and downstream of the fixing apparatus in the transport direction of the recording material so as to have a predetermined positional relationship therebetween, thereby detecting the wrapping of the recording material (For example, PTL 1 and PTL 2). If the leading end of a recording material P does not reach the outlet sensor within a predetermined time after passing through the inlet sensor, a control unit decides that the leading end of the recording material may have been wrapped around the fixing roller. Subsequently, the rotations of the fixing roller and the pressure roller are stopped to prevent the recording material from further entering the fixing apparatus.